The use of a cyclone to separate, mill, or dry material is known, and various applications of cyclones have been described in a number of prior art specifications. For example, U.S. Pat. No. 5,236,132 (Rowley) discloses a comminutor/dehydrator which incorporates a cyclone, as does U.S. Pat. No. 4,390,131 (Pickrel). U.S. Pat. No. 4,743,364 and No. 6,206,202 both disclose classifying/separating apparatus incorporating a cyclone. However, the prior art designs in general fail to provide fine control of processing conditions within the cyclone. This in turn limits the range of products which can be processed, and also limits the quality of the output product. Further, most if not all of the known comminuting/dehydrating cyclones operate only batch processes.